1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * Copyright (c) 2021 Hans de Goede <hdegoede@redhat.com> 4 * 5 * Driver for the LetSketch / VSON WP9620N drawing tablet. 6 * This drawing tablet is also sold under other brand names such as Case U, 7 * presumably this driver will work for all of them. But it has only been 8 * tested with a LetSketch WP9620N model. 9 * 10 * These tablets also work without a special HID driver, but then only part 11 * of the active area works and both the pad and stylus buttons are hardwired 12 * to special key-combos. E.g. the 2 stylus buttons send right mouse clicks / 13 * resp. "e" key presses. 14 * 15 * This device has 4 USB interfaces: 16 * 17 * Interface 0 EP 0x81 bootclass mouse, rdesc len 18, report id 0x08, 18 * Application(ff00.0001) 19 * This interface sends raw event input reports in a custom format, but only 20 * after doing the special dance from letsketch_probe(). After enabling this 21 * interface the other 3 interfaces are disabled. 22 * 23 * Interface 1 EP 0x82 bootclass mouse, rdesc len 83, report id 0x0a, Tablet 24 * This interface sends absolute events for the pen, including pressure, 25 * but only for some part of the active area due to special "aspect ratio" 26 * correction and only half by default since it assumes it will be used 27 * with a phone in portraid mode, while using the tablet in landscape mode. 28 * Also stylus + pad button events are not reported here. 29 * 30 * Interface 2 EP 0x83 bootclass keybd, rdesc len 64, report id none, Std Kbd 31 * This interfaces send various hard-coded key-combos for the pad buttons 32 * and "e" keypresses for the 2nd stylus button 33 * 34 * Interface 3 EP 0x84 bootclass mouse, rdesc len 75, report id 0x01, Std Mouse 35 * This reports right-click mouse-button events for the 1st stylus button 36 */ 37 #include <linux/device.h> 38 #include <linux/input.h> 39 #include <linux/hid.h> 40 #include <linux/module.h> 41 #include <linux/timer.h> 42 #include <linux/usb.h> 43 44 #include <asm/unaligned.h> 45 46 #include "hid-ids.h" 47 48 #define LETSKETCH_RAW_IF 0 49 50 #define LETSKETCH_RAW_DATA_LEN 12 51 #define LETSKETCH_RAW_REPORT_ID 8 52 53 #define LETSKETCH_PAD_BUTTONS 5 54 55 #define LETSKETCH_INFO_STR_IDX_BEGIN 0xc8 56 #define LETSKETCH_INFO_STR_IDX_END 0xca 57 58 #define LETSKETCH_GET_STRING_RETRIES 5 59 60 struct letsketch_data { 61 struct hid_device *hdev; 62 struct input_dev *input_tablet; 63 struct input_dev *input_tablet_pad; 64 struct timer_list inrange_timer; 65 }; 66 67 static int letsketch_open(struct input_dev *dev) 68 { 69 struct letsketch_data *data = input_get_drvdata(dev); 70 71 return hid_hw_open(data->hdev); 72 } 73 74 static void letsketch_close(struct input_dev *dev) 75 { 76 struct letsketch_data *data = input_get_drvdata(dev); 77 78 hid_hw_close(data->hdev); 79 } 80 81 static struct input_dev *letsketch_alloc_input_dev(struct letsketch_data *data) 82 { 83 struct input_dev *input; 84 85 input = devm_input_allocate_device(&data->hdev->dev); 86 if (!input) 87 return NULL; 88 89 input->id.bustype = data->hdev->bus; 90 input->id.vendor = data->hdev->vendor; 91 input->id.product = data->hdev->product; 92 input->id.version = data->hdev->bus; 93 input->phys = data->hdev->phys; 94 input->uniq = data->hdev->uniq; 95 input->open = letsketch_open; 96 input->close = letsketch_close; 97 98 input_set_drvdata(input, data); 99 100 return input; 101 } 102 103 static int letsketch_setup_input_tablet(struct letsketch_data *data) 104 { 105 struct input_dev *input; 106 107 input = letsketch_alloc_input_dev(data); 108 if (!input) 109 return -ENOMEM; 110 111 input_set_abs_params(input, ABS_X, 0, 50800, 0, 0); 112 input_set_abs_params(input, ABS_Y, 0, 31750, 0, 0); 113 input_set_abs_params(input, ABS_PRESSURE, 0, 8192, 0, 0); 114 input_abs_set_res(input, ABS_X, 240); 115 input_abs_set_res(input, ABS_Y, 225); 116 input_set_capability(input, EV_KEY, BTN_TOUCH); 117 input_set_capability(input, EV_KEY, BTN_TOOL_PEN); 118 input_set_capability(input, EV_KEY, BTN_STYLUS); 119 input_set_capability(input, EV_KEY, BTN_STYLUS2); 120 121 /* All known brands selling this tablet use WP9620[N] as model name */ 122 input->name = "WP9620 Tablet"; 123 124 data->input_tablet = input; 125 126 return input_register_device(data->input_tablet); 127 } 128 129 static int letsketch_setup_input_tablet_pad(struct letsketch_data *data) 130 { 131 struct input_dev *input; 132 int i; 133 134 input = letsketch_alloc_input_dev(data); 135 if (!input) 136 return -ENOMEM; 137 138 for (i = 0; i < LETSKETCH_PAD_BUTTONS; i++) 139 input_set_capability(input, EV_KEY, BTN_0 + i); 140 141 /* 142 * These are never send on the pad input_dev, but must be set 143 * on the Pad to make udev / libwacom happy. 144 */ 145 input_set_abs_params(input, ABS_X, 0, 1, 0, 0); 146 input_set_abs_params(input, ABS_Y, 0, 1, 0, 0); 147 input_set_capability(input, EV_KEY, BTN_STYLUS); 148 149 input->name = "WP9620 Pad"; 150 151 data->input_tablet_pad = input; 152 153 return input_register_device(data->input_tablet_pad); 154 } 155 156 static void letsketch_inrange_timeout(struct timer_list *t) 157 { 158 struct letsketch_data *data = from_timer(data, t, inrange_timer); 159 struct input_dev *input = data->input_tablet; 160 161 input_report_key(input, BTN_TOOL_PEN, 0); 162 input_sync(input); 163 } 164 165 static int letsketch_raw_event(struct hid_device *hdev, 166 struct hid_report *report, 167 u8 *raw_data, int size) 168 { 169 struct letsketch_data *data = hid_get_drvdata(hdev); 170 struct input_dev *input; 171 int i; 172 173 if (size != LETSKETCH_RAW_DATA_LEN || raw_data[0] != LETSKETCH_RAW_REPORT_ID) 174 return 0; 175 176 switch (raw_data[1] & 0xf0) { 177 case 0x80: /* Pen data */ 178 input = data->input_tablet; 179 input_report_key(input, BTN_TOOL_PEN, 1); 180 input_report_key(input, BTN_TOUCH, raw_data[1] & 0x01); 181 input_report_key(input, BTN_STYLUS, raw_data[1] & 0x02); 182 input_report_key(input, BTN_STYLUS2, raw_data[1] & 0x04); 183 input_report_abs(input, ABS_X, 184 get_unaligned_le16(raw_data + 2)); 185 input_report_abs(input, ABS_Y, 186 get_unaligned_le16(raw_data + 4)); 187 input_report_abs(input, ABS_PRESSURE, 188 get_unaligned_le16(raw_data + 6)); 189 /* 190 * There is no out of range event, so use a timer for this 191 * when in range we get an event approx. every 8 ms. 192 */ 193 mod_timer(&data->inrange_timer, jiffies + msecs_to_jiffies(100)); 194 break; 195 case 0xe0: /* Pad data */ 196 input = data->input_tablet_pad; 197 for (i = 0; i < LETSKETCH_PAD_BUTTONS; i++) 198 input_report_key(input, BTN_0 + i, raw_data[4] == (i + 1)); 199 break; 200 default: 201 hid_warn(data->hdev, "Warning unknown data header: 0x%02x\n", 202 raw_data[0]); 203 return 0; 204 } 205 206 input_sync(input); 207 return 0; 208 } 209 210 /* 211 * The tablets magic handshake to put it in raw mode relies on getting 212 * string descriptors. But the firmware is buggy and does not like it if 213 * we do this too fast. Even if we go slow sometimes the usb_string() call 214 * fails. Ignore errors and retry it a couple of times if necessary. 215 */ 216 static int letsketch_get_string(struct usb_device *udev, int index, char *buf, int size) 217 { 218 int i, ret; 219 220 for (i = 0; i < LETSKETCH_GET_STRING_RETRIES; i++) { 221 usleep_range(5000, 7000); 222 ret = usb_string(udev, index, buf, size); 223 if (ret > 0) 224 return 0; 225 } 226 227 dev_err(&udev->dev, "Max retries (%d) exceeded reading string descriptor %d\n", 228 LETSKETCH_GET_STRING_RETRIES, index); 229 return ret ? ret : -EIO; 230 } 231 232 static int letsketch_probe(struct hid_device *hdev, const struct hid_device_id *id) 233 { 234 struct device *dev = &hdev->dev; 235 struct letsketch_data *data; 236 struct usb_interface *intf; 237 struct usb_device *udev; 238 char buf[256]; 239 int i, ret; 240 241 if (!hid_is_usb(hdev)) 242 return -ENODEV; 243 244 intf = to_usb_interface(hdev->dev.parent); 245 if (intf->altsetting->desc.bInterfaceNumber != LETSKETCH_RAW_IF) 246 return -ENODEV; /* Ignore the other interfaces */ 247 248 udev = interface_to_usbdev(intf); 249 250 /* 251 * Instead of using a set-feature request, or even a custom USB ctrl 252 * message the tablet needs this elaborate magic reading of USB 253 * string descriptors to kick it into raw mode. This is what the 254 * Windows drivers are seen doing in an USB trace under Windows. 255 */ 256 for (i = LETSKETCH_INFO_STR_IDX_BEGIN; i <= LETSKETCH_INFO_STR_IDX_END; i++) { 257 ret = letsketch_get_string(udev, i, buf, sizeof(buf)); 258 if (ret) 259 return ret; 260 261 hid_info(hdev, "Device info: %s\n", buf); 262 } 263 264 for (i = 1; i <= 250; i++) { 265 ret = letsketch_get_string(udev, i, buf, sizeof(buf)); 266 if (ret) 267 return ret; 268 } 269 270 ret = letsketch_get_string(udev, 0x64, buf, sizeof(buf)); 271 if (ret) 272 return ret; 273 274 ret = letsketch_get_string(udev, LETSKETCH_INFO_STR_IDX_BEGIN, buf, sizeof(buf)); 275 if (ret) 276 return ret; 277 278 /* 279 * The tablet should be in raw mode now, end with a final delay before 280 * doing further IO to the device. 281 */ 282 usleep_range(5000, 7000); 283 284 ret = hid_parse(hdev); 285 if (ret) 286 return ret; 287 288 data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL); 289 if (!data) 290 return -ENOMEM; 291 292 data->hdev = hdev; 293 timer_setup(&data->inrange_timer, letsketch_inrange_timeout, 0); 294 hid_set_drvdata(hdev, data); 295 296 ret = letsketch_setup_input_tablet(data); 297 if (ret) 298 return ret; 299 300 ret = letsketch_setup_input_tablet_pad(data); 301 if (ret) 302 return ret; 303 304 return hid_hw_start(hdev, HID_CONNECT_HIDRAW); 305 } 306 307 static const struct hid_device_id letsketch_devices[] = { 308 { HID_USB_DEVICE(USB_VENDOR_ID_LETSKETCH, USB_DEVICE_ID_WP9620N) }, 309 { } 310 }; 311 MODULE_DEVICE_TABLE(hid, letsketch_devices); 312 313 static struct hid_driver letsketch_driver = { 314 .name = "letsketch", 315 .id_table = letsketch_devices, 316 .probe = letsketch_probe, 317 .raw_event = letsketch_raw_event, 318 }; 319 module_hid_driver(letsketch_driver); 320 321 MODULE_AUTHOR("Hans de Goede <hdegoede@redhat.com>"); 322 MODULE_LICENSE("GPL"); 323